Process fo reclaiming rubber.



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HARRY BARRTNGER. COX, 01E BEJDFOEJD HILLS, NEW YORK.

PROCESS OF RECLAIMING RUBBER.

No Drawing.

filed July 29, 1914.

To all whom it may concern Be it known that T, HARRY BARRINGER Cox, acitizen of the United States, residing in Bedford Hills, county ofWestchester, and State of New York, have invented a new and usefulProcess of Reclaiming Rubber, of which the following is a division of myformer application, filed January 16, 1913, Se rial No. 742,402.

The methods now in use for the recovery of rubber stock from oldvulcanized rubber generally involve the subjection of the rubber undervarious conditions of heat, with or without pressure, to aqueoussolutions of one kind or another. These processes not merely injure thegum. itself, but also affect to a very substantial extent the substanceswith which it is compounded, so that the resulting stock is very muchinferior to the original stock and differs. from it substantially withrespect to many of its elements. Said processes moreover are cumbersome,laborious and expensive.

T have discovered a process whereby the stock produced is maintained inclose approximation to the original stock retaining the originalqualities of the gum approximately unimpaired, and also the originalcompounds so far as their usefulness is concei'ned. My process moreover.is neither cumbersome, laborious nor expensive.

Although I do not wish to be understood as limiting myself to theattainment of all of the above-results, or to the most perfect form ofmy process, I will now proceed'to describe the process as I at presentprefer to carry it out.

T first prepare what ll will herein refer to as my resin solution, whichll believe to be new per se, and which ll prefer to prepare as follows:I purify commercial rosin by heating it until it boils and continuingthe boiling until I evaporate the containedwater and other'volatilesubstances. This boiling lasts about two hours and is continued untilthe resin stops foaming. I then permit the resin to cool and grind it toa fine powder. I next dissolve the resin at ordinary temperature ingasolene and allow the insoluble parts of the resin to settle and decantoil the solution. I may use two pounds of the purified resin to 100pounds of gasolene,

where the resin solution is to be employed for the treatment ofautomobile 'tire tread stock. For lower grades of stock ahigherpercentage of resin to the gasolene is prefer- Specification ofLetters Patent.

Patented (Bet. ll, imlti.

Original application filed January 16, 1913, Serial No. 742,402. Dividedand'this application Serial No. 853,803.

rubber stock to be treated to about the fineness of coarse sand tofacilitate absorption of the resin solution. ll put the stock in an opentray and pour over it suflicient resin solution.

In determining the amount of resin solution to be used for a givenquantity of vulcanized stockT calculate the amount of resin that lbelieve to be necessary to reimburse the stock with the freed resin thathas been alfected by vulcanization, and employ an amount of resinsolution containing this calculated amount of resin. T have found inpractice that a proportion of about 3 pounds of resin to over 100 poundsof ground automobile tire tread stock will answer the purpose.

As the resin solution is absorbed the stock will swell say from two tofour times its bulk, depending upon the quality of the stock, and alsoupon the amount of gasolene employed as the vehicle for carrying theresin into the stock. I let the mass stand preferably until it hasstopped swelling, which may take about an hour. ll next heat gently anduniformly until the mass becomes tacky. For this purpose I prefer a heatabout from 190 to 200 F. for about from four to twenty hours, dependingupon the quality of the stock. The greater the mineral matter in thestock the lesstime is required. Or the length of time of this heatingmay be lessened to about one hour by subjecting the mass to live steamof about twenty pounds pressure. This reduction in time is, however, atthe expense of a somewhat lower quality of product because of theincreased heat. lln this step, length of time is more or less asubstitute for heat so that the operation might take place at ordinarytemperature in about from ten to fifteen days. ll next remove thegasolene from the mass either by distillation, by vacuum extraction, orby live steam. T next dry the stock, if necessary, and it is then incondition to be milled.

The recovered stock thus produced differs from the present ordinarydevulcanized stock in the following respects: The tensile strength ofpresent ordinary devulcanized' the original, Whereas the tensilestrength of my product is above and may be as high as 90% of theoriginal.

The stock is characterized by ease and rapidity of milling. The gum isapproximately unimpaired. The mineral compounds remain to such an extentthat the stock does not have to be recompounded. Even though certain ofthe mineral compounds, as for example the litharge, have been changed bythe original vulcanization they still may retain their efficiency asfillers in their changed form.

Compared with original unvulcanized stock, my stock differs in not beingsoluble in gasolene, whereas original unvulcanized stock is solubletherein. Moreover by application of heat my stock may be reduced to aliquid solution in said resin solution, whereas under similar conditionsoriginal iinvulcanized stock is reduced to a viscous consistency.

\Vhatever kind of resin I employ in making my resin solution, I mayimprove said solution by adding thereto a small percentage of vulcanizedgum stock which has been reduced to a liquid by the resin solution andheat as above described.

Instead of making the resin solution by the use of resin as abovedescribed, it may be made by the use of rubber resin, or in other wordsby resin obtained by extraction of rubber or analogous gums, whichrubber resin is now largely a waste product.

By a proper arrangement of apparatus the gasolene which is used as thevehicle of the resin in one operation of my process may be recovered asit escapes from the stock and may be used over again in subsequentoperations of my process.

I do not wish to be understood as limiting myself to gasolene as acarrier medium for the resin to the exclusion of other carrier mediumsfor resin. I may use naphtha or kerosene as a carrier medium fortheresin;

In case the old vulcanized rubber to be treated is combined with fiber,I remove the fiber preliminarily in my treatment of the rubber.

Having produced my recovered stock as aforesaid and milled the same, Imay prepare it for revulcanization by mixing it with the calculatedamount of sulfur necessary.

The approximation of my recovered stock to the original is such that itis revulcanizable in the same time and temperature as that taken in theoriginal vulcanization. Therefore. a factory employing my process maywith impunity mix its recovered stock with its new stock because both ofthem are adapted to the same time and temperature of vulcanization,therefore the conditions which properly vulcanize one would properlyvulcanize the other when the two are mixed.

\Vhat I claim and desire to secure by Letters Patent of the UnitedStates is 1. The process of recovering rubber stock from vulcanizedrubber which consists in treating the same with a hydrocarbon solutionof rubber resin.

The process of recovering rubber stock from vulcanized rubber whichconsists in impregnating the same with rubber resin.

3. The process of recovering rubber stock from vulcanized rubber whichconsists in treating the same with a solution of rubber resin.

4. The process of recovering rubber stock from vulcanized rubber whichconsists in treating the same with a resin solution together with asolution of vulcanized gum in a resin solution.

In testimony whereof I have hereunto signed my name in the presence oftwo subscribing witnesses.

HARRY BARRINGER COX.

Witnesses:

ALFREEDA G. THAANUM, ADELAIDE FOSHAY.

